JP3351071B2 - Alignment method and apparatus - Google Patents
Alignment method and apparatusInfo
- Publication number
- JP3351071B2 JP3351071B2 JP31470293A JP31470293A JP3351071B2 JP 3351071 B2 JP3351071 B2 JP 3351071B2 JP 31470293 A JP31470293 A JP 31470293A JP 31470293 A JP31470293 A JP 31470293A JP 3351071 B2 JP3351071 B2 JP 3351071B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- intensity
- diffracted light
- alignment
- detection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7092—Signal processing
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7073—Alignment marks and their environment
- G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、被測定物のアライメン
ト、特に回折格子を配列したアライメントマークを持つ
ウェハ等のアライメント方法及び装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment method for an object to be measured, and more particularly to an alignment method and apparatus for a wafer having an alignment mark in which diffraction gratings are arranged.
【０００２】[0002]
【従来の技術】従来、半導体素子の製造には、ウェハを
順次ステップ移動させながら縮小投影露光を行うステッ
パが用いられている。半導体素子は、ウェハ上の回路パ
ターンとレティクル上の回路パターンとを順次重ね合わ
せて露光を繰り返すことによって製造される。2. Description of the Related Art Conventionally, in the manufacture of semiconductor devices, a stepper for performing reduced projection exposure while sequentially moving a wafer stepwise has been used. A semiconductor element is manufactured by sequentially superposing a circuit pattern on a wafer and a circuit pattern on a reticle and repeating exposure.
【０００３】近年、この回路パターンは半導体素子の処
理能力の向上に伴ってますます微細化、高密度化されて
いるので、ウェハとレティクルは、より高精度にアライ
メントされる必要があり、このためには、まず、ウェハ
上の回路パターンの位置を高精度に測定する必要があ
る。しかし、ウェハにはレジストが塗布されており、こ
のレジストの塗布むらにより、例えば特開昭６１−１２
８１０６号公報のように回折光アライメント検出方式を
採用する場合には、アライメントマークの中心位置とア
ライメントマークの像の中心位置がレジストの塗布むら
によってシフトする場合があった。以下図７以下を用い
て説明する。In recent years, since the circuit pattern has been increasingly miniaturized and densified in accordance with the improvement in the processing capability of semiconductor devices, the wafer and the reticle must be aligned with higher precision. First, it is necessary to measure the position of the circuit pattern on the wafer with high accuracy. However, the wafer is coated with a resist.
In the case of employing the diffracted light alignment detection method as disclosed in Japanese Patent No. 8106, the center position of the alignment mark and the center position of the image of the alignment mark may be shifted due to unevenness in application of the resist. This will be described below with reference to FIG.
【０００４】回折光検出では、コヒーレンシーの高いレ
ーザ５を光源として使用する。Ｈｅ−Ｎｅレーザや半導
体レーザ等、露光装置の用途や計測の対象物によって最
適な波長のレーザが選択される。レーザ５より出射した
光は、６、７の凸レンズａ，ｂとピンホール８から成る
ビームエキスパンダにより所望のビーム径に成形した
後、ビームスプリッタ１０、リレーレンズ１１、先端ミ
ラー１２を介して、レティクル１のパターンをウェハ２
の上に結像する縮小レンズ４の入射瞳１３の中心に入射
し、ウェハ２の上に設けられた回折格子２ｂにほぼ垂直
の方向から照射される。In the detection of diffracted light, a laser 5 having high coherency is used as a light source. A laser having an optimal wavelength is selected depending on the application of the exposure apparatus or the object to be measured, such as a He-Ne laser or a semiconductor laser. The light emitted from the laser 5 is shaped into a desired beam diameter by a beam expander composed of 6, 7 convex lenses a and b and a pinhole 8, and then is passed through a beam splitter 10, a relay lens 11, and a tip mirror 12. Reticle 1 pattern on wafer 2
Is incident on the center of the entrance pupil 13 of the reduction lens 4 which forms an image on the wafer 2, and is irradiated from a direction substantially perpendicular to the diffraction grating 2b provided on the wafer 2.
【０００５】アライメントマーク２ｂは、図８に示すよ
うに、サイズａのマーク要素２ｃが複数個、等ピッチ
（ピッチｂ）かつ、一直線上に配置されており、これに
レーザ照明光を照射すると、（数１）式に示す関係の方
向θｎに回折光Ｄ±１，Ｄ±２が発生する。As shown in FIG. 8, the alignment mark 2b has a plurality of mark elements 2c each having a size a and arranged at an equal pitch (pitch b) and on a straight line. Diffracted light D ± 1 and D ± 2 are generated in the direction θn of the relationship shown in Expression (1).
【０００６】[0006]
【数１】 (Equation 1)
【０００７】回折光は、縮小レンズ４、先端ミラー１
２、リレーレンズ１１、ビームスプリッタ１０、対物レ
ンズ１４を介して、空間フィルタ１５に達し、ここで、
所望の次数の回折光（通常は±１次回折光）を選択的に
通過させた後、円筒レンズ１６によりＹ方向に圧縮し、
リニアイメージセンサ１７上に結像し、図９のような回
折光強度分布３６を得る。そして、ウェハ２がＸ方向に
移動すれば、リニアイメージセンサ１７上のアライメン
トマーク２ｂの像位置も変化し、精密な位置決め量の測
定が可能となる。[0007] The diffracted light is reduced by the reduction lens 4 and the tip mirror 1.
2. Reach the spatial filter 15 via the relay lens 11, the beam splitter 10, and the objective lens 14, where:
After selectively passing a desired order of diffracted light (usually ± 1st order diffracted light), it is compressed in the Y direction by a cylindrical lens 16,
An image is formed on the linear image sensor 17 to obtain a diffracted light intensity distribution 36 as shown in FIG. When the wafer 2 moves in the X direction, the image position of the alignment mark 2b on the linear image sensor 17 also changes, so that a precise positioning amount can be measured.
【０００８】[0008]
【発明が解決しようとする課題】実際の露光装置におけ
るアライメントでは、図１０に示すように、レジストが
ないときの回折光強度分布３７はレジストがあるときの
回折光強度分布３６とεだけ検出位置がシフトする。In the alignment in an actual exposure apparatus, as shown in FIG. 10, the diffracted light intensity distribution 37 when there is no resist is equal to the diffracted light intensity distribution 36 when resist is present and the detection position is ε. Shifts.
【０００９】これは図１１に示すように、ウェハ２上の
凹凸段差によって形成されるアライメントマーク２ｂの
上にレジスト２ａが塗布されているために、プロセス条
件、即ち、アライメントマーク２ｂの段差ｔ１、あるい
はレジスト２ａの塗布膜厚ｔ２によっては、塗布むらが
発生し、レジスト２ａによる多重反射によって、リニア
イメージセンサ１７で検出される検出波形が非対称とな
り、アライメントマーク２ｂの像の中心位置の検出に誤
差が生じるという問題があるためである。This is because, as shown in FIG. 11, the resist 2a is applied on the alignment mark 2b formed by the uneven steps on the wafer 2, so that the process conditions, that is, the step t1 of the alignment mark 2b, Alternatively, depending on the coating film thickness t2 of the resist 2a, coating unevenness occurs, and due to multiple reflection by the resist 2a, the detection waveform detected by the linear image sensor 17 becomes asymmetric, and an error occurs in the detection of the center position of the image of the alignment mark 2b. This is because there is a problem in that
【００１０】本発明の目的は、上記従来技術の持つ課題
を解決し、アライメントマーク２ｂの像の中心位置の検
出誤差εを正確に測定できるアライメント方法及びその
装置を提供することにある。An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an alignment method and an alignment apparatus capable of accurately measuring the detection error ε of the center position of the image of the alignment mark 2b.
【００１１】[0011]
【課題を解決するための手段】上記目的を達成するため
に、本発明のアライメント方法及びその装置は、予めレ
ジストを塗布したアライメントマーク付きのウェハに照
射光を照射したときの±１次回折光の相対強度差Ｓとレ
ジスト膜厚ｄ、ウェハ下地層の複素屈折率ｎ、アライメ
ントマークの段差ｋとの関係を求めておき、レジスト膜
厚ｄ、ウェハ下地層の複素屈折率ｎ、マーク段差ｋの各
組合せ毎に、±１次回折光の相対強度差Ｓと検出誤差ε
との関係をシミュレーション又は実験により求める。以
下シミュレーションで求めた相関曲線をシミュレーショ
ン曲線、実験で求めた相関曲線を実験曲線と呼ぶ。In order to achieve the above object, an alignment method and apparatus according to the present invention provide a method for irradiating a wafer with an alignment mark, which has been coated with a resist beforehand, with ± 1st-order diffracted light. The relationship between the relative intensity difference S and the resist film thickness d, the complex refractive index n of the wafer underlayer, and the step k of the alignment mark is obtained in advance, and the resist film thickness d, the complex refractive index n of the wafer underlayer, and the mark step k are calculated. For each combination, the relative intensity difference S of ± 1st-order diffracted light and the detection error ε
Is determined by simulation or experiment. Hereinafter, the correlation curve obtained by the simulation is called a simulation curve, and the correlation curve obtained by the experiment is called an experimental curve.
【００１２】次に、量産ウェハの各製造工程毎に±１次
回折光の相対強度差Ｓを測定する。前記相対強度差Ｓを
各製造工程毎のシミュレーション曲線又は実験曲線と照
合して各製造工程毎の検出誤差εを求める。この検出誤
差εを回折光アライメント検出方式の制御処理回路にフ
ィードフォワードし、検出位置の補正ができるようにし
ている。Next, the relative intensity difference S of ± 1st-order diffracted light is measured for each manufacturing process of a mass-produced wafer. The relative intensity difference S is compared with a simulation curve or an experimental curve for each manufacturing process to determine a detection error ε for each manufacturing process. This detection error ε is fed forward to a control processing circuit of the diffraction light alignment detection system so that the detection position can be corrected.
【００１３】[0013]
【作用】本発明の作用を図１２により説明する。図１２
は本発明の原理を示すブロック図である。The operation of the present invention will be described with reference to FIG. FIG.
FIG. 1 is a block diagram showing the principle of the present invention.
【００１４】前記アライメント方法及びその装置におい
て、図１２（ａ）に示すように、予め多種類のウェハの
アライメントマークの検出方向のレジスト膜厚データｄ
（ｘ），検出方向の複素屈折率データｎ（ｘ），検出方
向のマーク段差データｋ（ｘ）及び±１次回折光の正規
化相対強度差データＳ（ｘ）を測定しておき、シミュレ
ーション計算又は実験によるデータ収集により、レジス
ト膜厚データｄ（ｘ），複素屈折率データｎ（ｘ），マ
ーク段差データｋ（ｘ），±１次回折光の正規化相対強
度差データＳ（ｘ）を変数とする、検出誤差εを求める
シミュレーション曲線又は実験曲線ε（ｘ）（関数Ｆ）
を求めておく。In the above-described alignment method and apparatus, as shown in FIG. 12A, resist thickness data d in the detection directions of alignment marks of various types of wafers are previously determined.
(X), the complex refractive index data n (x) in the detection direction, the mark step data k (x) in the detection direction, and the normalized relative intensity difference data S (x) of the ± 1st-order diffracted light are measured in advance, and simulation calculation is performed. Alternatively, the resist film thickness data d (x), the complex refractive index data n (x), the mark step data k (x), and the normalized relative intensity difference data S (x) of the ± 1st-order diffracted light are obtained by data collection through experiments. A simulation curve or an experimental curve ε (x) (function F) for finding the detection error ε
Ask for.
【００１５】次に図１２（ｂ）において、第１の状態と
して照射光の右側に発生する＋１次回折光強度を検出す
る場合を考察する。このときの照射光の強度をＳａ、＋
１次回折光の強度をＶａとすると、一定の照射光強度に
正規化した＋１次回折光強度Ｉａは次の（数２）式のよ
うになる。Next, in FIG. 12B, the case where the intensity of the + 1st-order diffracted light generated on the right side of the irradiation light is detected as the first state will be considered. The intensity of the irradiation light at this time is Sa, +
Assuming that the intensity of the first-order diffracted light is Va, the + 1st-order diffracted light intensity Ia normalized to a constant irradiation light intensity is represented by the following equation (2).
【００１６】[0016]
【数２】 (Equation 2)
【００１７】今度は第２の状態として、照射光の左側に
発生する−１次回折光強度を検出する場合を考察する。
このときの照射光の強度をＳｂ、−１次回折光の強度を
Ｖｂとすると、一定の照射光強度に正規化した−１次回
折光の強度Ｉｂは次の（数３）式のようになる。Now, as the second state, consider the case of detecting the intensity of the -1st-order diffracted light generated on the left side of the irradiation light.
Assuming that the intensity of the irradiation light at this time is Sb and the intensity of the -1st-order diffracted light is Vb, the intensity Ib of the -1st-order diffracted light normalized to a constant irradiation light intensity is expressed by the following equation (3).
【００１８】[0018]
【数３】 (Equation 3)
【００１９】従って、ウェハに垂直に照射光を照射した
ときの±１次回折光の正規化された相対強度差Ｓは（数
４）式のようになる。Therefore, the normalized relative intensity difference S of the ± 1st-order diffracted light when the irradiation light is irradiated on the wafer vertically is expressed by the following equation (4).
【００２０】[0020]
【数４】 (Equation 4)
【００２１】そこで、図１２（ａ）で予め求めた検出誤
差を求めるシミュレーション曲線又は実験曲線ε（ｘ）
の関数Ｆに図１２（ｂ）で測定した±１次回折光正規化
相対強度差Ｓとそのときのレジスト膜厚ｄ、複素屈折率
ｎ、マーク段差ｋを代入すれば、検出誤差εが求められ
る。Therefore, a simulation curve or an experimental curve ε (x) for obtaining a detection error previously obtained in FIG.
By substituting the ± 1st-order diffracted light normalized relative intensity difference S measured in FIG. 12 (b) and the resist thickness d, complex refractive index n, and mark step k at that time into the function F, the detection error ε can be obtained. .
【００２２】従って、前記処理により得られた検出誤差
εを回折光アライメント検出方式の制御処理回路にフィ
ードフォワードすれば、検出位置の補正ができる。Therefore, if the detection error ε obtained by the above processing is fed forward to the control processing circuit of the diffracted light alignment detection system, the detection position can be corrected.
【００２３】即ち、図１のアライメント光学系におい
て、予めレジスト膜厚ｄ、ウェハ下地層の複素屈折率
ｎ、マーク段差ｋの組合せ毎に、±１次回折光正規化相
対強度差Ｓと検出誤差εの関係を示すシミュレーション
曲線又は実験曲線で求めておくことにより、量産ウェハ
の各製造工程毎に±１次回折光正規化相対強度差Ｓを測
定すれば、検出誤差εを測定できるというものである。
前記検出誤差εを回折光アライメント検出方式の制御処
理回路にフィードフォワードすると、検出位置の補正が
できる。That is, in the alignment optical system shown in FIG. 1, the ± 1st-order diffracted light normalized relative intensity difference S and the detection error ε are determined in advance for each combination of the resist film thickness d, the complex refractive index n of the wafer underlayer, and the mark step k. Is obtained by using a simulation curve or an experimental curve showing the relationship, the detection error ε can be measured by measuring the ± 1st-order diffracted light normalized relative intensity difference S for each manufacturing process of a mass-produced wafer.
When the detection error ε is fed forward to a control processing circuit of the diffraction light alignment detection method, the detection position can be corrected.
【００２４】[0024]
【実施例】以下に本発明の実施例を説明する。Embodiments of the present invention will be described below.
【００２５】図１において、１はレティクル、２はウェ
ハ、２ａはレジスト、２ｂはアライメントマーク、３は
ステージ、４は縮小レンズ、５はレーザ、６は凸レンズ
ａ、７は凸レンズｂ、８はピンホール、９はミラー、１
０ａ，１０ｂ，１０ｃ，１０ｄはビームスプリッタ、１
１はリレーレンズ、１２は先端ミラー、１３は入射瞳、
１４は対物レンズ、１５は空間フィルタ、１６は円筒レ
ンズ、１７はリニアイメージセンサ、１８はシャッタ
ー、１９ａ、１９ｂは光強度検出器、２０は制御処理回
路、２１はステージ駆動回路、２２はレジスト膜厚測定
器、２３は複素屈折率測定器、２４はマーク段差測定器
である。In FIG. 1, 1 is a reticle, 2 is a wafer, 2a is a resist, 2b is an alignment mark, 3 is a stage, 4 is a reduction lens, 5 is a laser, 6 is a convex lens a, 7 is a convex lens b, and 8 is a pin. Hall, 9 is a mirror, 1
0a, 10b, 10c, 10d are beam splitters, 1
1 is a relay lens, 12 is a front end mirror, 13 is an entrance pupil,
14 is an objective lens, 15 is a spatial filter, 16 is a cylindrical lens, 17 is a linear image sensor, 18 is a shutter, 19a and 19b are light intensity detectors, 20 is a control processing circuit, 21 is a stage drive circuit, and 22 is a resist film. A thickness measuring device, 23 is a complex refractive index measuring device, and 24 is a mark step measuring device.
【００２６】この構成で垂直方向の偏光（Ｓ偏光）を持
つレーザ５から出射した光は、６，７の凸レンズａ，ｂ
とピンホール８から成るビームエキスパンダにより所望
のビーム径に成形した後、ビームスプリッタ１０ａ，１
０ｂ、リレーレンズ１１、先端ミラー１２、シャッター
１８を介して、レティクル１のパターンをウェハ２の上
に結像する縮小レンズ４の入射瞳１３の中心に入射し、
ウェハ２の上に設けられたアライメントマーク２ｂにほ
ぼ垂直の方向から照射される。In this configuration, light emitted from the laser 5 having vertically polarized light (S-polarized light) passes through 6, 7 convex lenses a and b.
After being formed into a desired beam diameter by a beam expander including a pinhole 8 and a beam splitter 10a, 1
0b, via the relay lens 11, the tip mirror 12, and the shutter 18, the light enters the center of the entrance pupil 13 of the reduction lens 4 for imaging the pattern of the reticle 1 on the wafer 2,
Irradiation is performed on the alignment mark 2b provided on the wafer 2 from a direction substantially perpendicular to the alignment mark 2b.
【００２７】アライメントマーク２ｂは、複数個、等ピ
ッチで一直線上に配置されており、これにレーザ照明光
を照射すると、数１に示す関係の方向θｎに回折光Ｄ±
１，Ｄ±２が発生する。A plurality of alignment marks 2b are arranged on a straight line at an equal pitch. When the alignment marks 2b are irradiated with laser illumination light, the diffracted light D ±
1, D ± 2 occurs.
【００２８】回折光は、縮小レンズ４、シャッター１
８、ビームスプリッタ１０ｃ，１０ｄ、先端ミラー１
２、リレーレンズ１１、ビームスプリッタ１０ｂ、対物
レンズ１４を介して、空間フィルタ１５に達し、ここ
で、所望の次数の回折光（通常は±１次回折光）を選択
的に通過させた後、円筒レンズ１６によりＹ方向に圧縮
し、リニアイメージセンサ１７上に結像する。そして、
ウェハ２がＸ方向に移動すれば、リニアイメージセンサ
１７上のアライメントマーク２ｂの像の中心位置も変化
し、精密な位置決め量の測定が可能となる。The diffracted light passes through the reduction lens 4 and the shutter 1
8, beam splitters 10c and 10d, tip mirror 1
2. After reaching a spatial filter 15 via a relay lens 11, a beam splitter 10b, and an objective lens 14, where a diffracted light of a desired order (usually ± 1st order diffracted light) is selectively passed, The image is compressed in the Y direction by the lens 16 and forms an image on the linear image sensor 17. And
If the wafer 2 moves in the X direction, the center position of the image of the alignment mark 2b on the linear image sensor 17 also changes, and a precise positioning amount can be measured.
【００２９】しかし、レジスト塗布むらが存在するとき
は、レジスト２ａによる多重干渉によってリニアイメー
ジセンサ１７で検出されるアライメントマーク２ｂの像
の検出波形が非対称となり、検出誤差εが生ずる。そこ
で検出位置での±１次回折光の正規化された相対強度差
Ｓとレジスト膜厚ｄ、複素屈折率ｎ、アライメントマー
ク２ｂの段差ｋがわかれば、制御処理回路２０において
予めレジスト膜厚測定器２２、複素屈折率測定器２３、
マーク段差測定器２４より得られた各プロセス条件毎の
相対強度差Ｓと検出誤差εとの関係を示すシミュレーシ
ョン曲線又は実験曲線に検出位置での相対強度差Ｓ0を
代入することにより、検出誤差ε0が求められる。However, when the resist coating unevenness exists, the detection waveform of the image of the alignment mark 2b detected by the linear image sensor 17 becomes asymmetric due to the multiple interference by the resist 2a, and a detection error ε occurs. Therefore, if the normalized relative intensity difference S of the ± 1st-order diffracted light at the detection position, the resist film thickness d, the complex refractive index n, and the step k of the alignment mark 2b are known, the control processing circuit 20 determines in advance the resist film thickness measuring device. 22, complex refractometer 23,
By substituting the relative intensity difference S 0 at the detection position into a simulation curve or an experimental curve indicating the relationship between the relative intensity difference S for each process condition and the detection error ε obtained from the mark level measuring device 24, the detection error ε 0 is determined.
【００３０】検出位置での±１次回折光の相対強度差Ｓ
0は以下の方法により求める。ウェハ２より発生する±
１次回折光のうち、どちらか片方はシャッター１８で遮
光し、もう一方の遮光していない＋１次回折光又は−１
次回折光は、その一部がビームスプリッタ１０ｃ又は１
０ｄで反射し、光強度検出器１９ａに入射する。従っ
て、瞬間的にシャッター１８を作動させて、＋１次回折
光又は−１次回折光のみを光強度検出器１９ａに入射さ
せれば、ほぼ同時に±１次回折光強度を検出できる。The relative intensity difference S of the ± 1st-order diffracted light at the detection position
0 is obtained by the following method. ± generated from wafer 2
Either one of the first-order diffracted lights is shielded by the shutter 18 and the other is not + 1-order diffracted light or -1.
Part of the second-order diffracted light is the beam splitter 10c or 1
The light is reflected at 0d and enters the light intensity detector 19a. Therefore, if the shutter 18 is instantaneously operated and only the + 1st-order diffracted light or the -1st-order diffracted light is incident on the light intensity detector 19a, the ± 1st-order diffracted light intensity can be detected almost simultaneously.
【００３１】又、同時にビームスプリッタ１０ａでは、
レーザ照射光の一部が反射して、光強度検出器１９ｂに
入射する。このため、光強度検出器１９ａで検出される
＋１次回折光強度又は−１次回折光強度を光強度検出器
１９ｂで検出されるレーザ照射光強度で除算してやれ
ば、レーザ照射光強度の変動を除去（正規化）でき、高
精度な±１次回折光強度が検出できる。このようにして
求めた正規化した＋１次回折光強度をＩａ0、正規化し
た−１次回折光強度をＩｂ0とすると、±１次回折光の
正規化相対強度差Ｓ0は（Ｉａ0−Ｉｂ0）／（Ｉａ0＋Ｉ
ｂ0）により求められる。At the same time, in the beam splitter 10a,
A part of the laser irradiation light is reflected and enters the light intensity detector 19b. Therefore, if the + 1st-order or -1st-order diffracted light intensity detected by the light intensity detector 19a is divided by the laser irradiation light intensity detected by the light intensity detector 19b, the fluctuation of the laser irradiation light intensity is removed ( Normalization), and a highly accurate ± 1st-order diffracted light intensity can be detected. Assuming that the normalized + 1st-order diffracted light intensity thus obtained is Ia 0 and the normalized −1st-order diffracted light intensity is Ib 0 , the normalized relative intensity difference S 0 of ± 1st-order diffracted light is (Ia 0 −Ib 0). ) / (Ia 0 + I
b 0 ).
【００３２】本実施例によれば、レーザ出力強度の変動
を常時モニタして正規化した±１次回折光の強度の検出
とアライメントマーク２ｂの像位置の検出を同時に行え
るため、レジスト塗布むらがある場合でも常に正確にア
ライメントマーク２ｂの位置検出ができるという効果が
ある。According to this embodiment, the fluctuation of the laser output intensity is constantly monitored, and the detection of the normalized intensity of the ± 1st-order diffracted light and the detection of the image position of the alignment mark 2b can be performed at the same time. Even in this case, there is an effect that the position of the alignment mark 2b can always be accurately detected.
【００３３】またビームスプリッタ１０ｃ，１０ｄの透
過率がそれぞれＴ1，Ｔ2と異なる場合は＋１次回折光，
−１次回折光の正規化された相対強度差Ｉａ0，Ｉｂ0を
それぞれＴ1・（１−Ｔ1），Ｔ2・（１−Ｔ2）・Ｔ1で
割って補正を行えば、正確な±１次回折光の強度を求め
ることができる。When the transmittances of the beam splitters 10c and 10d are different from T 1 and T 2 , respectively,
Correcting by dividing the normalized relative intensity differences Ia 0 and Ib 0 of the −1st order diffracted light by T 1 · (1−T 1 ) and T 2 · (1−T 2 ) · T 1 , respectively, gives an accurate result. The intensity of the ± 1st-order diffracted light can be determined.
【００３４】＋１次回折光または−１次回折光の遮光に
用いるシャッター１８の切り替えには数秒以内で済むこ
とから、数秒以内のレーザ出力強度変動量が無視できる
ほど小さければ、実効的に検出器の感度は同一とみなす
ことができる。レーザの出力強度変動に高周波成分があ
る場合は時間平均をとる方法や高安定化電源を使用する
方法もある。Since the switching of the shutter 18 used for blocking the + 1st-order or -1st-order diffracted light can be done within a few seconds, if the fluctuation of the laser output intensity within a few seconds is negligibly small, the sensitivity of the detector is effectively increased. Can be considered the same. When the output intensity fluctuation of the laser has a high-frequency component, there are a method of taking a time average and a method of using a highly stabilized power supply.
【００３５】なお、レジスト塗布むら量δを０．０２μ
ｍとしたときの±１次回折光の正規化された相対強度差
Ｓは０．０２となるため、１／１０の精度が必要とした
場合、０．２％の光強度の測定精度が必要である。The resist coating unevenness amount δ is set to 0.02 μm.
Since the normalized relative intensity difference S of the ± 1st-order diffracted light when m is 0.02, when accuracy of 1/10 is required, measurement accuracy of 0.2% light intensity is required. is there.
【００３６】本実施例では、光強度の検出に±１次回折
光を用いているが、１次回折光の強度が齢場合は高次の
回折光を用いてもよい。本実施例のシミュレーション方
式では、検出誤差ε0を求めるのに±１次回折光の正規
化された相対強度差（Ｉａ0−Ｉｂ0）／（Ｉａ0＋Ｉ
ｂ0）を用いているが、単純にＩａ0−Ｉｂ0やＩａ0／Ｉ
ｂ0を用いてもよい。In this embodiment, ± 1st-order diffracted light is used for detecting the light intensity. However, when the intensity of the 1st-order diffracted light is old, higher-order diffracted light may be used. In the simulation method of the present embodiment, the normalized relative intensity difference (Ia 0 −Ib 0 ) / (Ia 0 + I) of ± first-order diffracted light is used to obtain the detection error ε 0.
b 0 ), but simply Ia 0 −Ib 0 or Ia 0 / I
b 0 may be used.
【００３７】本実施例では、光源にコヒーレンシーの高
いレーザ光を用いているが、入射瞳１３で集光させる手
段を設けることにより、ｅ線（波長４８０ｎｍ），ｄ線
（波長５７７ｎｍ）や広帯域波長照明を用いてもよい。In this embodiment, a laser beam having a high coherency is used as the light source. However, by providing a means for converging the light at the entrance pupil 13, the e-line (wavelength 480 nm), d-line (wavelength 577 nm) and broadband wavelength are used. Lighting may be used.
【００３８】図２はアライメントマーク上のレジストの
塗布むらを示す図である。FIG. 2 is a view showing the unevenness of application of the resist on the alignment mark.
【００３９】いま、アライメントマーク２ｂの形状を表
わす関数をｆ（ｘ）（アライメントマーク中心座標
ｘc）、アライメントマーク２ｂ上に塗布されたレジス
ト２ａの形状を示す関数をｇ（ｘ）、検出位置での塗布
むら量をδ0とする。このレジスト塗布むら量δ0はレジ
ストの非対称性を表わすパラメータであり、ｆ（ｘ）−
ｆ（ｘ）により検出方向のレジスト膜厚ｄの変化が求め
られれば、容易に求められる。[0039] Now, the function representing the shape of the alignment marks 2b f (x) (the alignment mark center coordinates x c), the function representing the shape of the coated resist 2a on the alignment mark 2b g (x), the detection position Δ 0 is the amount of uneven coating. The resist coating unevenness δ 0 is a parameter representing the asymmetry of the resist, and is represented by f (x) −
If the change in the resist film thickness d in the detection direction is obtained by f (x), it can be easily obtained.
【００４０】次に図３、図４により図１の検出誤差ε0
を間接的に測定する方法について説明する。Next, FIG. 3 and FIG. 4 show the detection error ε 0 of FIG.
A method for indirectly measuring is described.
【００４１】図３は、あるプロセス条件におけるレジス
ト塗布むら量δと±１次回折光の強度Ｉａ，Ｉｂの関係
を示す計算例図である。レジスト塗布むら量δが大きく
なると、＋１次回折光Ｉａと−１次回折光Ｉｂの強度差
Ｉａ−Ｉｂは大きくなる。従って、前記強度差Ｉａ−Ｉ
ｂとレジスト塗布むら量δの間には、レジスト塗布むら
量δ＝０μｍ〜０．０９μｍの範囲では相関がある。FIG. 3 is a calculation example diagram showing the relationship between the resist coating unevenness amount δ and the ± I-order diffraction light intensities Ia and Ib under certain process conditions. As the resist coating unevenness δ increases, the intensity difference Ia-Ib between the + 1st-order diffracted light Ia and the −1st-order diffracted light Ib increases. Therefore, the intensity difference Ia-I
There is a correlation between b and the resist coating unevenness δ in the range of the resist coating unevenness δ = 0 μm to 0.09 μm.
【００４２】図４は±１次回折光の相対強度差Ｓと検出
誤差εの関係を示す図である。FIG. 4 is a diagram showing the relationship between the relative intensity difference S of ± 1st-order diffracted light and the detection error ε.
【００４３】図４（ａ）は図３の＋１次回折光Ｉａと−
１次回折光Ｉｂの相対強度差Ｓ＝（Ｉａ−Ｉｂ）／（Ｉ
ａ＋Ｉｂ）とレジスト塗布むら量δとの関係を示す。図
３に示すシミュレーション結果により、レジスト塗布む
ら量δ＝０μｍ〜０．０９μｍ、±１次回折光の相対強
度差Ｓ＝０〜０．０２の範囲内で比例関係にあることが
わかる。FIG. 4 (a) shows the + 1st-order diffracted light Ia and-of FIG.
Relative intensity difference S of primary diffracted light Ib = (Ia−Ib) / (I
a + Ib) and the resist coating unevenness amount δ are shown. The simulation results shown in FIG. 3 indicate that the resist coating unevenness amount δ = 0 μm to 0.09 μm and the relative intensity difference S of ± 1st order diffracted light S = 0 to 0.02 in a proportional relationship.
【００４４】図４（ｂ）は検出誤差εとレジスト塗布む
ら量δとの関係を示したシミュレーション曲線である。FIG. 4B is a simulation curve showing the relationship between the detection error ε and the resist coating unevenness amount δ.
【００４５】図４（ｃ）は図４（ａ）と図４（ｂ）のシ
ミュレーションを元に生成した検出誤差εと±１次回折
光の相対強度差Ｓとの関係を示す図である。レジスト膜
厚ｄ，複素屈折率ｎ，マーク段差ｋの値の組合せによ
り、図中で示す条件ｂ，条件ｃの曲線となる。FIG. 4C is a diagram showing the relationship between the detection error ε generated based on the simulations of FIGS. 4A and 4B and the relative intensity difference S of ± first-order diffracted light. The combination of the values of the resist film thickness d, the complex refractive index n, and the mark step k results in curves of the conditions b and c shown in the figure.
【００４６】図５は本発明によるアライメント方法及び
その装置の第２の実施例を示す図である。FIG. 5 is a view showing a second embodiment of the alignment method and apparatus according to the present invention.
【００４７】図において、１はレティクル、２はウェ
ハ、２ａはレジスト、２ｂはアライメントマーク、３は
ステージ、４は縮小レンズ、５はレーザ、６は凸レンズ
ａ、７は凸レンズｂ、８はピンホール、９はミラー、１
０ａ，１０ｂ，１０ｃ，１０ｄはビームスプリッタ、１
１はリレーレンズ、１２は先端ミラー、１３は入射瞳、
１４は対物レンズ、１５は空間フィルタ、１６は円筒レ
ンズ、１７はリニアイメージセンサ、１８はシャッタ
ー、１８ａ，１８ｂ，１８ｃは遮光部、１９は光強度検
出器、２０は制御処理回路、２１はステージ駆動回路、
２２はレジスト膜厚測定器、２３は複素屈折率測定器、
２４はマーク段差測定器である。In the drawing, 1 is a reticle, 2 is a wafer, 2a is a resist, 2b is an alignment mark, 3 is a stage, 4 is a reduction lens, 5 is a laser, 6 is a convex lens a, 7 is a convex lens b, and 8 is a pinhole. , 9 are mirrors, 1
0a, 10b, 10c, 10d are beam splitters, 1
1 is a relay lens, 12 is a front end mirror, 13 is an entrance pupil,
14 is an objective lens, 15 is a spatial filter, 16 is a cylindrical lens, 17 is a linear image sensor, 18 is a shutter, 18a, 18b, and 18c are light shielding units, 19 is a light intensity detector, 20 is a control processing circuit, and 21 is a stage. Drive circuit,
22 is a resist film thickness measuring device, 23 is a complex refractive index measuring device,
Reference numeral 24 denotes a mark step measuring device.
【００４８】この構成で垂直方向の偏光（Ｓ偏光）を持
つレーザ５から出射した光は、６，７の凸レンズａ，ｂ
とピンホール８から成るビームエキスパンダにより所望
のビーム径に成形した後、ビームスプリッタ１０ａ、リ
レーレンズ１１、先端ミラー１２、ビームスプリッタ１
０ｂ、シャッター１８を介して、レティクル１のパター
ンをウェハ２の上に結像する縮小レンズ４の入射瞳１３
の中心に入射し、ウェハ２の上に設けられたアライメン
トマーク２ｂにほぼ垂直の方向から照射される。In this configuration, light emitted from the laser 5 having vertically polarized light (S-polarized light) is emitted from 6, 7 convex lenses a and b.
After shaping into a desired beam diameter by a beam expander including a pinhole 8 and a beam splitter 10a, a relay lens 11, a tip mirror 12, a beam splitter 1
0b, the entrance pupil 13 of the reduction lens 4 for imaging the pattern of the reticle 1 on the wafer 2 via the shutter 18.
And irradiates the alignment mark 2b provided on the wafer 2 from a direction substantially perpendicular to the alignment mark 2b.
【００４９】アライメントマーク２ｂは、複数個、等ピ
ッチで一直線上に配置されており、これにレーザ照明光
を照射すると、数１に示す関係の方向θｎに回折光Ｄ±
１，Ｄ±２が発生する。A plurality of alignment marks 2b are arranged on a straight line at an equal pitch. When the alignment marks 2b are irradiated with laser illumination light, the diffracted light D ±
1, D ± 2 occurs.
【００５０】回折光は、縮小レンズ４、シャッター１
８、ビームスプリッタ１０ｃ，１０ｄ、先端ミラー１
２、リレーレンズ１１、ビームスプリッタ１０ａ、対物
レンズ１４を介して、空間フィルタ１５に達し、ここ
で、所望の次数の回折光（通常は±１次回折光）を選択
的に通過させた後、円筒レンズ１６によりＹ方向に圧縮
し、リニアイメージセンサ１７上に結像する。そして、
ウェハ２がＸ方向に移動すれば、リニアイメージセンサ
１７上のアライメントマーク２ｂの像位置も変化し、精
密な位置決め量の測定が可能となる。The diffracted light passes through the reduction lens 4 and the shutter 1
8, beam splitters 10c and 10d, tip mirror 1
2. After reaching a spatial filter 15 via a relay lens 11, a beam splitter 10a, and an objective lens 14, where a diffracted light of a desired order (usually ± 1st-order diffracted light) is selectively passed, The image is compressed in the Y direction by the lens 16 and forms an image on the linear image sensor 17. And
When the wafer 2 moves in the X direction, the image position of the alignment mark 2b on the linear image sensor 17 also changes, and a precise positioning amount can be measured.
【００５１】しかし、レジスト塗布むらが存在するとき
は、アライメントマーク２ｂの像の検出波形が非対称と
なり、検出誤差εが生じる。そこで、図１と同じ方法で
検出位置での±１次回折光の正規化された相対強度差Ｓ
0と各プロセス条件毎のシミュレーション曲線又は実験
曲線を制御処理回路２０で照合することにより、検出誤
差ε0がわかる。However, when the resist coating unevenness exists, the detected waveform of the image of the alignment mark 2b becomes asymmetric, and a detection error ε occurs. Therefore, the normalized relative intensity difference S of the ± 1st-order diffracted light at the detection position in the same manner as in FIG.
By comparing 0 with a simulation curve or an experimental curve for each process condition in the control processing circuit 20, the detection error ε 0 can be found.
【００５２】検出位置での±１次回折光強度は以下の方
法により求める。第１の状態として照射光の右側に発生
する＋１次回折光を検出する場合を考える。この場合は
−１次回折光と照射光は必要ないため、シャッター１８
の遮光部１８ａと１８ｃで−１次回折光と照射光を同時
に遮光し、＋１次回折光の一部をビームスプリッタ１０
ｃで反射させて光強度検出器１９で検出する。The ± 1st-order diffracted light intensity at the detection position is obtained by the following method. The case where the + 1st-order diffracted light generated on the right side of the irradiation light is detected as the first state will be considered. In this case, since the -1st-order diffracted light and irradiation light are not required, the shutter 18
-1st-order diffracted light and irradiation light are simultaneously shielded by the light-shielding portions 18a and 18c, and a part of the + 1st-order diffracted light is
The light is reflected by c and detected by the light intensity detector 19.
【００５３】第２の状態として照射光の左側に発生する
−１次回折光を検出する場合を考える。この場合は＋１
次回折光は必要ないため、シャッター１８の遮光部１８
ｂで＋１次回折光を遮光し、−１次回折光の一部をビー
ムスプリッタ１０ｄで反射させて光強度検出器１９で検
出する。照射光も遮光する必要があるが、遮光すると回
折光自体が発生しなくなるため、後で照射光強度分を差
し引く方法をとる。As a second state, consider the case of detecting the -1st-order diffracted light generated on the left side of the irradiation light. In this case +1
Since the next-order diffracted light is not required,
The + 1st-order diffracted light is blocked by b, and a part of the -1st-order diffracted light is reflected by the beam splitter 10d and detected by the light intensity detector 19. Irradiation light also needs to be shielded, but if the light is shielded, no diffracted light itself is generated. Therefore, a method of subtracting the irradiation light intensity later is adopted.
【００５４】照射光強度を検出するときは、ウェハ２よ
り発生する±１次回折光の両方をシャッター１８の遮光
部１８ａと１８ｂで同時に遮光し、照射光の一部をビー
ムスプリッタ１０ｂで反射させて光強度検出器１９で検
出する。When detecting the irradiation light intensity, both the ± 1st-order diffracted light generated from the wafer 2 are shielded simultaneously by the light shielding portions 18a and 18b of the shutter 18, and a part of the irradiation light is reflected by the beam splitter 10b. The light intensity is detected by a light intensity detector 19.
【００５５】従って、瞬間的にシャッター１８を作動さ
せて、＋１次回折光、照射光及び−１次回折光＋照射光
を光強度検出器１９に入射させれば、ほぼ同時に±１次
回折光強度及び照射光強度を検出できる。Therefore, if the shutter 18 is instantaneously actuated and the + 1st-order diffracted light, irradiation light and -1st-order diffracted light + irradiation light enter the light intensity detector 19, the ± 1st-order diffracted light intensity and irradiation Light intensity can be detected.
【００５６】このため、光強度検出器１９で検出される
＋１次回折光強度又は−１次回折光強度を同一の光強度
検出器１９で検出される照射光強度で除算してやれば、
照射光強度の変動を除去（正規化）でき、高精度な回折
光強度が検出できる。このようにして求めた正規化した
＋１次回折光強度をＩａ0、正規化した−１次回折光強
度をＩｂ0とすると、±１次回折光の正規化相対強度差
Ｓは（Ｉａ0−Ｉｂ0）／（Ｉａ0＋Ｉｂ0）により求めら
れる。Therefore, if the + 1st-order or -1st-order diffracted light intensity detected by the light intensity detector 19 is divided by the irradiation light intensity detected by the same light intensity detector 19,
Fluctuations in irradiation light intensity can be removed (normalized), and highly accurate diffraction light intensity can be detected. Assuming that the normalized + 1st-order diffracted light intensity thus obtained is Ia 0 and the normalized −1st-order diffracted light intensity is Ib 0 , the normalized relative intensity difference S of ± 1st-order diffracted light is (Ia 0 −Ib 0 ). / (Ia 0 + Ib 0 ).
【００５７】本実施例によれば、回折光強度と照射光強
度の検出を同一の検出器で行えるため、検出器の器差の
影響を除去できるという効果がある。According to the present embodiment, since the intensity of the diffracted light and the intensity of the irradiation light can be detected by the same detector, the effect of the instrumental difference of the detector can be eliminated.
【００５８】またビームスプリッタ１０ｂ，１０ｃ，１
０ｄの透過率がそれぞれＴ1，Ｔ2，Ｔ3と異なる場合
は、光強度検出器１９で検出される照射光、＋１時回折
光、−１次回折光の強度をそれぞれ（１−Ｔ2）・Ｔ4，
Ｔ2・（１−Ｔ3），Ｔ2 2・Ｔ3・（１−Ｔ4）で割って補
正を行えば、正確な±１次回折光の強度を求めることが
できる。The beam splitters 10b, 10c, 1
If the transmittance of the 0d is different from T 1, T 2, T 3, respectively, the irradiation light detected by the light intensity detector 19, + 1:00 diffracted light, -1 the intensity of diffracted light, respectively (1-T 2)・ T 4 ,
T 2 · (1-T 3 ), by performing the correction is divided by T 2 2 · T 3 · ( 1-T 4), and obtain the intensity of accurate ± 1-order diffracted light.
【００５９】＋１次回折光または−１次回折光または照
射光遮光に用いるシャッター１８の遮光部１８ａ，１８
ｂ，１８ｃの切り替えには数秒以内で済むことから、数
秒以内のレーザ出力強度変動量が無視できるほど小さけ
れば、実効的に同一検出器で同時に前記３つの強度を測
定したことになるため、正確な±１次回折光及び照射光
の強度を求めることができる。The light-shielding portions 18a and 18 of the shutter 18 used to shield the + 1st-order or -1st-order diffracted light or the irradiation light.
Since the switching between b and 18c can be done within a few seconds, if the variation in the laser output intensity within a few seconds is negligibly small, it means that the same three detectors are effectively measured simultaneously with the same detector. The intensity of the ± 1st-order diffracted light and irradiation light can be obtained.
【００６０】図６は本発明によるアライメント方法及び
その装置の第３の実施例を示す図である。FIG. 6 is a view showing a third embodiment of the alignment method and apparatus according to the present invention.
【００６１】図において、１はレティクル、２はウェ
ハ、２ａはレジスト、２ｂはアライメントマーク、３は
ステージ、４は縮小レンズ、５はレーザ、９はミラー、
１０ａ，１０ｂ，１０ｃ，１０ｄ，１０ｅはビームスプ
リッタ、１１はリレーレンズ、１３は入射瞳、１４は対
物レンズ、１５は空間フィルタ、１６は円筒レンズ、１
７はリニアイメージセンサ、１８ａ，１８ｂはシャッタ
ー、１９ａ，１９ｂは光強度検出器、２０は制御処理回
路、２１はステージ駆動回路、２２はレジスト膜厚測定
器、２３は複素屈折率測定器、２４はマーク段差測定
器、３５はコリメータレンズ、１１１，１１２，１２
１，１２２は光路である。In the figure, 1 is a reticle, 2 is a wafer, 2a is a resist, 2b is an alignment mark, 3 is a stage, 4 is a reduction lens, 5 is a laser, 9 is a mirror,
10a, 10b, 10c, 10d, and 10e are beam splitters, 11 is a relay lens, 13 is an entrance pupil, 14 is an objective lens, 15 is a spatial filter, 16 is a cylindrical lens, 1
7 is a linear image sensor, 18a and 18b are shutters, 19a and 19b are light intensity detectors, 20 is a control processing circuit, 21 is a stage drive circuit, 22 is a resist film thickness measuring device, 23 is a complex refractive index measuring device, 24 Is a mark step measuring device, 35 is a collimator lens, 111, 112, 12
1, 122 is an optical path.
【００６２】この構成で垂直方向の偏光（Ｓ偏光）を持
つレーザ５から出射した光は、ビームスプリッタ１０ａ
で透過光と反射光に分かれ、反射光は光強度検出器１９
ａに入射する。ビームスプリッタ１０ａを透過した光は
ビームスプリッタ１０ｂに入射する。ビームスプリッタ
１０ｂに入射した光はさらに透過光と反射光に分かれ
る。In this configuration, light emitted from the laser 5 having vertically polarized light (S-polarized light) is transmitted to the beam splitter 10a.
Is divided into transmitted light and reflected light, and the reflected light is reflected by the light intensity detector 19.
a. The light transmitted through the beam splitter 10a enters the beam splitter 10b. The light incident on the beam splitter 10b is further divided into transmitted light and reflected light.
【００６３】いま第１の状態としてビームスプリッタ１
０ｂを透過する光について記述する。ビームスプリッタ
１０ｂを透過する光はミラー９、シャッター１８ａ，１
８ｂ、ビームスプリッタ１０ｃを通り、コリメータレン
ズ３５に入射する。コリメータレンズ３５に入射した光
は光路１１１を通り、縮小レンズ４を介して光路１２１
を通り、１次回折角の半分のθ／２でウェハ２に入射す
る。Now, as the first state, the beam splitter 1
0b is described. The light passing through the beam splitter 10b is reflected by the mirror 9, the shutters 18a, 1
8b, passes through the beam splitter 10c and enters the collimator lens 35. The light incident on the collimator lens 35 passes through the optical path 111, and passes through the optical path 121 via the reduction lens 4.
And enters the wafer 2 at θ / 2 which is half of the first-order diffraction angle.
【００６４】このときアライメントマーク２ｂによって
発生する１次回折光は、照射光と同じ光路１２１を戻
り、ビームスプリッタ１０ｃに入射する。尚、同時に発
生する正反射光（０次回折光）は、光路１２２，１１２
を戻るが、シャッター１８ｂによって遮光されるため、
ビームスプリッタ１０ｄには入射しない。ビームスプリ
ッタ１０ｃを反射した光は、ビームスプリッタ１０ｅに
入射する。ビームスプリッタ１０ｅを反射した光は光強
度検出器１９ｂに入射する。At this time, the first-order diffracted light generated by the alignment mark 2b returns along the same optical path 121 as the irradiation light and enters the beam splitter 10c. Incidentally, the specularly reflected light (0th-order diffracted light) generated at the same time is transmitted through the optical paths 122 and 112.
Is returned, but because the light is blocked by the shutter 18b,
It does not enter the beam splitter 10d. The light reflected by the beam splitter 10c enters the beam splitter 10e. The light reflected by the beam splitter 10e enters the light intensity detector 19b.
【００６５】ビームスプリッタ１０ｅを透過した光はリ
レーレンズ１１、対物レンズ１４を介して空間フィルタ
１５に達し、ここで１次回折光のみを選択的に透過させ
た後、円筒レンズ１６によりＹ方向に圧縮し、リニアイ
メージセンサ１７上に結像し、図９のような検出波形３
６を得る。そして、ウェハ２がＸ方向に移動すれば、リ
ニアイメージセンサ１７上のアライメントマーク２ｂの
像位置が変化し、アライメントマーク２ｂの中心位置の
測定が可能となる。The light transmitted through the beam splitter 10e reaches the spatial filter 15 via the relay lens 11 and the objective lens 14, where only the first-order diffracted light is selectively transmitted, and then compressed in the Y direction by the cylindrical lens 16. Then, an image is formed on the linear image sensor 17 and the detection waveform 3 shown in FIG.
Get 6. When the wafer 2 moves in the X direction, the image position of the alignment mark 2b on the linear image sensor 17 changes, and the center position of the alignment mark 2b can be measured.
【００６６】次に第２の状態としてビームスプリッタ１
０ｂを反射する光について記述する。ビームスプリッタ
１０ｂを反射する光は、シャッター１８ａ，１８ｂ、ビ
ームスプリッタ１０ｄを通り、コリメータレンズ３５に
入射する。コリメータレンズ３５を通過した光は光路１
１２を通り、縮小レンズ４を介して光路１２２を通り、
１次回折角の半分のθ／２でウェハ２に入射する。Next, the beam splitter 1 is set as the second state.
The light reflecting 0b will be described. The light reflected by the beam splitter 10b passes through the shutters 18a and 18b and the beam splitter 10d and enters the collimator lens 35. The light that has passed through the collimator lens 35 is
12, through the optical path 122 via the reduction lens 4,
The light is incident on the wafer 2 at θ / 2, which is half the primary diffraction angle.
【００６７】このときアライメントマーク２ｂによって
発生する１次回折光は、照射光と同じ光路１２２を戻
り、ビームスプリッタ１０ｄに入射する。尚、同時に発
生する正反射光（０次回折光）は光路１２１，１１１を
戻るが、シャッター１８ｂによって遮光されるため、ビ
ームスプリッタ１０ｃに入射しない。ビームスプリッタ
１０ｄを反射した光は、ビームスプリッタ１０ｅに入射
する。At this time, the first-order diffracted light generated by the alignment mark 2b returns along the same optical path 122 as the irradiation light and enters the beam splitter 10d. The specular light (0-order diffracted light) generated at the same time returns to the optical paths 121 and 111, but is not blocked by the shutter 18b, so that it does not enter the beam splitter 10c. The light reflected by the beam splitter 10d enters the beam splitter 10e.
【００６８】この後は、第１の状態と同様の光路を進
み、光強度検出器１９ｂで１次回折光の強度を、リニア
イメージセンサ１７でアライメントマーク２ｂの像位置
をそれぞれ検出する。Thereafter, the light travels in the same optical path as in the first state, and the intensity of the first-order diffracted light is detected by the light intensity detector 19b, and the image position of the alignment mark 2b is detected by the linear image sensor 17.
【００６９】従って、制御処理回路２０によって、シャ
ッター１８ａ，１８ｂを瞬間的に作動させれば、光強度
検出器１９ａ，１９ｂで検出される第１，第２の状態の
照射光・１次回折光強度から検出位置での正規化された
１次回折光の相対強度差Ｓ0が求められ、同時にアライ
メントマーク２ｂの像位置の検出もできる。この後の処
理は図１と同様に行われ、予めレジスト膜厚測定器２
２、複素屈折率測定器２３、マーク段差測定器２４より
得られた各プロセス条件毎のシミュレーション曲線又は
実験曲線と検出位置での前記相対強度差Ｓ0を制御処理
回路２０で照合することにより、検出誤差ε0がわか
る。Accordingly, when the shutters 18a and 18b are instantaneously operated by the control processing circuit 20, the intensity of the irradiation light and the first-order diffracted light in the first and second states detected by the light intensity detectors 19a and 19b is obtained. , The relative intensity difference S 0 of the normalized first-order diffracted light at the detection position is obtained, and the image position of the alignment mark 2b can be detected at the same time. Subsequent processing is performed in the same manner as in FIG.
2. The control processing circuit 20 compares the relative intensity difference S 0 at the detection position with a simulation curve or an experimental curve for each process condition obtained from the complex refractive index measuring device 23 and the mark level measuring device 24, The detection error ε 0 is known.
【００７０】本実施例では、ウェハ２への入射角が１次
回折角の半分であるため、空気の密度変化による光路シ
フトの影響を受けにくいという効果がある。In this embodiment, since the angle of incidence on the wafer 2 is half of the first-order diffraction angle, there is an effect that the optical path shift is less affected by a change in the density of air.
【００７１】本発明は図１において縮小レンズ４を介さ
ずにコリメータレンズ３５から直接アライメントマーク
２ｂに照射光を入射させることにより、プロキシミティ
露光装置に適用することもできる。The present invention can be applied to a proximity exposure apparatus by irradiating irradiation light from the collimator lens 35 directly to the alignment mark 2b without passing through the reduction lens 4 in FIG.
【００７２】[0072]
【発明の効果】以上、本発明によれば、レジスト塗布膜
厚、ウェハ下地層の複素屈折率、アライメントマークの
マーク段差といったプロセス条件の変化に対しても、量
産ウェハの各製造工程毎に±１次回折光の相対強度差を
各プロセス条件毎の前記相対強度差と検出誤差との関係
を示すシミュレーション曲線又は実験曲線に代入するだ
けで、検出誤差の測定ができるために、従来、回折光ア
ライメント検出方式の問題点の１つであったレジストの
塗布むらによるアライメントマークの中心位置の検出誤
差を補正することができ、線幅０．５μｍ以下のＬＳＩ
の重ねあわせ精度が向上するという効果がある。As described above, according to the present invention, even when the process conditions such as the resist coating film thickness, the complex refractive index of the wafer underlayer, and the mark level difference of the alignment mark are changed, each manufacturing process of the mass-produced wafer is ±. Since the detection error can be measured only by substituting the relative intensity difference of the first-order diffracted light into a simulation curve or an experimental curve showing the relationship between the relative intensity difference and the detection error for each process condition, conventionally, the diffraction light alignment An LSI having a line width of 0.5 μm or less can correct a detection error of the center position of an alignment mark due to uneven coating of a resist, which was one of the problems of the detection method.
There is an effect that the superposition accuracy of is improved.
【００７３】また重ねあわせ精度の向上に伴って、歩留
まり高くＬＳＩの生産ができるため、高実装密度のＬＳ
Ｉの生産が可能になるという効果がある。Further, with the improvement of the overlay accuracy, it is possible to produce an LSI with a high yield.
There is an effect that production of I becomes possible.
【図１】本発明によるアライメント方法及びその装置の
第１の実施例を示す概略構成図である。FIG. 1 is a schematic configuration diagram showing a first embodiment of an alignment method and apparatus according to the present invention.
【図２】アライメントマーク上のレジストの塗布むらを
示す図である。FIG. 2 is a diagram showing uneven coating of a resist on an alignment mark.
【図３】レジスト塗布むら量と±１次回折光の強度との
関係を示す計算例を示す図である。FIG. 3 is a diagram illustrating a calculation example showing the relationship between the resist coating unevenness amount and the intensity of ± 1st-order diffracted light.
【図４】プロセス条件を変えたときの±１次回折光の相
対強度差と検出誤差の関係を示す計算例を示す図であ
る。FIG. 4 is a diagram illustrating a calculation example showing a relationship between a relative intensity difference of ± 1st-order diffracted light and a detection error when a process condition is changed.
【図５】本発明によるアライメント方法及びその装置の
第２の実施例を示す概略構成図である。FIG. 5 is a schematic configuration diagram showing a second embodiment of the alignment method and apparatus according to the present invention.
【図６】本発明によるアライメント方法及びその装置の
第３の実施例を示す概略構成図である。FIG. 6 is a schematic configuration diagram showing a third embodiment of the alignment method and apparatus according to the present invention.
【図７】従来のアライメント装置の一例を示す概略構成
図である。FIG. 7 is a schematic configuration diagram illustrating an example of a conventional alignment apparatus.
【図８】回折光検出の原理を示す図である。FIG. 8 is a diagram illustrating the principle of diffraction light detection.
【図９】回折光検出波形の検出例を示す図である。FIG. 9 is a diagram illustrating a detection example of a diffraction light detection waveform.
【図１０】レジストによる回折光検出波形のシフトを示
す図である。FIG. 10 is a diagram showing a shift of a diffraction light detection waveform by a resist.
【図１１】実際のアライメントマークの断面形状を示す
図である。FIG. 11 is a diagram showing a cross-sectional shape of an actual alignment mark.
【図１２】本発明の原理を示すブロック図である。FIG. 12 is a block diagram showing the principle of the present invention.
１…レティクル、 ２…ウェハ、 ２ａ…レジスト、 ２ｂ…回折格子、 ３…ステージ、 ４…縮小レンズ、 ５…レーザ、 ６…凸レンズａ、 ７…凸レンズｂ、 ８…ピンホール、 ９…ミラー、 １０ａ，１０ｂ，１０ｃ，１０ｄ…ビームスプリッタ、 １１…リレーレンズ、 １２…先端ミラー、 １３…入射瞳、 １４…対物レンズ、 １５…空間フィルタ、 １６…円筒レンズ、 １７…リニアイメージセンサ、 １８…シャッター、 １９ａ，１９ｂ…光強度検出器、 ２０…制御処理回路、 ２１…ステージ駆動回路、 ２２…レジスト膜厚測定器、 ２３…複素屈折率測定器、 ２４…マーク段差測定器。 DESCRIPTION OF SYMBOLS 1 ... Reticle, 2 ... Wafer, 2a ... Resist, 2b ... Diffraction grating, 3 ... Stage, 4 ... Reduction lens, 5 ... Laser, 6 ... Convex lens a, 7 ... Convex lens b, 8 ... Pinhole, 9 ... Mirror, 10a , 10b, 10c, 10d: beam splitter, 11: relay lens, 12: tip mirror, 13: entrance pupil, 14: objective lens, 15: spatial filter, 16: cylindrical lens, 17: linear image sensor, 18: shutter, 19a, 19b: light intensity detector, 20: control processing circuit, 21: stage driving circuit, 22: resist film thickness measuring device, 23: complex refractive index measuring device, 24: mark step measuring device.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平４−303916（ＪＰ，Ａ) 特開 平５−326371（ＪＰ，Ａ) 特開 平２−103401（ＪＰ，Ａ) 特開 平２−7511（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01B 11/00 H01L 21/027 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-303916 (JP, A) JP-A-5-326371 (JP, A) JP-A-2-103401 (JP, A) JP-A-2-103 7511 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) G01B 11/00 H01L 21/027
Claims (12)
ストの塗布された回折光検出用アライメントマークに、
所定の角度で、照射光を照射したときに発生する正反射
光を除いた回折光を用いて回折光検出用アライメントマ
ークの像の中心位置を検出するアライメント方法におい
て、前記回折光検出用アライメントマークから発生する
左右方向の回折光の強度と前記照射光の強度の比から求
められる正規化された左右の回折光強度の相対強度差
と、予め得られた回折光検出用アライメントマークの段
差データとレジスト膜厚データと複素屈折率データより
生成されるシミュレーション曲線又は実験曲線からレジ
ストの塗布むらによるアライメントマークの像の中心位
置の検出誤差を算出し、前記検出誤差を回折光アライメ
ント検出方式の制御処理回路にフィードフォワードし、
検出位置の補正をすることを特徴とするアライメント方
法。1. A diffraction light detection alignment mark coated with a resist formed on an object to be detected,
A predetermined angle, the alignment method for detecting the center position of the image of the alignment mark for diffraction light detection using the diffracted light excluding the specular reflection light generated when irradiating the irradiation light, the alignment mark for diffraction light detection The relative intensity difference between the normalized left and right diffracted light intensities determined from the ratio of the intensity of the irradiated light and the intensity of the diffracted light in the left and right directions, and the step data of the diffracted light detection alignment mark obtained in advance. A detection error of the center position of the image of the alignment mark due to uneven coating of the resist is calculated from a simulation curve or an experimental curve generated from the resist film thickness data and the complex refractive index data, and the detection error is controlled by a diffraction light alignment detection method. Feed forward to the circuit,
An alignment method, comprising correcting a detection position.
て、回折光検出用アライメントマークに、垂直に照射光
を照射し、このとき照射光の光路の左右方向に発生する
回折光の強度と前記照射光の強度をそれぞれ検出するこ
とを特徴とするアライメント方法。2. The alignment method according to claim 1, wherein the irradiation light is irradiated vertically on the alignment mark for detecting the diffracted light, and the intensity of the diffracted light generated in the left and right direction of the optical path of the irradiation light is determined. Alignment method characterized by detecting respective intensities of light.
て、照射光の光路の左右方向に発生する回折光の強度と
前記照射光の強度とを同時に検出することを特徴とする
アライメント方法。3. The alignment method according to claim 2, wherein the intensity of the diffracted light generated in the left-right direction of the optical path of the irradiation light and the intensity of the irradiation light are simultaneously detected.
て、前記左右の方向のうち、少なくとも一方についてそ
れぞれの照射光の強度とこの照射光により発生する前記
回折光の強度を同一の検出器で検出することを特徴とす
るアライメント方法。4. The alignment method according to claim 2, wherein at least one of the left and right directions detects the intensity of each irradiation light and the intensity of the diffraction light generated by the irradiation light with the same detector. An alignment method, comprising:
て、照射光を左右方向から交互に照射することを特徴と
するアライメント方法。5. The alignment method according to claim 1, wherein irradiation light is irradiated alternately from left and right.
ト方法において、前記回折光が１次回折光であることを
特徴とするアライメント方法。6. The alignment method according to claim 2, wherein the diffracted light is a first-order diffracted light.
ストの塗布された回折光検出用アライメントマークに、
所定の角度で、照射光を照射する手段と、このとき発生
する正反射光を除いた回折光を用いて回折光検出用アラ
イメントマークの像の中心位置を検出する手段とを具備
するアライメント装置において、前記回折光検出用アラ
イメントマークから発生する左右方向の回折光の強度と
前記照射光の強度をそれぞれ検出する手段と、前記照射
光の照射により前記回折光検出用アライメントマークか
ら発生する前記左右方向の回折光強度と前記照射光の強
度の比から正規化された左右方向の回折光強度を求める
手段と、前記左右方向の正規化された回折光強度より正
規化された左右の相対強度差を求める手段と、予め得ら
れた回折光検出用アライメントマークの段差データとレ
ジスト膜厚データと複素屈折率データよりシミュレーシ
ョン曲線又は実験曲線を生成する手段と、前記の正規化
された左右の相対強度差と前記シミュレーション曲線又
は実験曲線を照合してレジストの塗布むらによるアライ
メントマークの像の中心位置の検出誤差を算出する手段
と、前記検出誤差を回折光アライメント検出方式の制御
処理回路にフィードフォワードし検出位置の補正をする
手段とを具備することを特徴とするアライメント装置。7. A diffraction light detection alignment mark coated with a resist formed on an object whose position is to be detected,
An alignment apparatus comprising: means for irradiating irradiation light at a predetermined angle; and means for detecting a center position of an image of a diffraction light detection alignment mark using diffracted light excluding specular light generated at this time. Means for detecting the intensity of the diffracted light in the horizontal direction generated from the alignment mark for diffraction light detection and the intensity of the irradiation light, respectively, and the direction in the horizontal direction generated from the alignment mark for diffraction light detection by irradiation of the irradiation light Means for obtaining a normalized left-right diffracted light intensity from the ratio of the diffracted light intensity and the irradiation light intensity, and a left-right relative intensity difference normalized from the left-right normalized diffracted light intensity. Means for obtaining a simulation curve or experiment from the step data, resist film thickness data, and complex refractive index data of the alignment mark for diffraction light detection obtained in advance. Means for generating a line, and means for calculating the detection error of the center position of the image of the alignment mark due to uneven coating of the resist by comparing the normalized relative intensity difference between the left and right and the simulation curve or the experimental curve, Means for feed-forwarding the detection error to a control processing circuit of a diffraction light alignment detection system to correct a detection position.
て、回折光検出用アライメントマークに垂直に照射光を
照射する手段と、このとき照射光の光路の左右方向に発
生する回折光の強度と前記照射光の強度をそれぞれ検出
する手段とを具備することを特徴とするアライメント装
置。8. The alignment apparatus according to claim 7, wherein the means for irradiating the irradiation light perpendicularly to the alignment mark for detecting the diffracted light, the intensity of the diffracted light generated in the left and right direction of the optical path of the irradiation light, and the irradiation. Means for detecting respective light intensities.
て、照射光の光路の左右方向に発生する回折光の強度と
前記照射光の強度とを同時に検出する手段を具備するこ
とを特徴とするアライメント装置。9. An alignment apparatus according to claim 8, further comprising means for simultaneously detecting the intensity of the diffracted light generated in the left and right direction of the optical path of the irradiation light and the intensity of the irradiation light. .
て、前記左右の方向のうち、少なくとも一方についてそ
れぞれの照射光の強度とこの照射光により発生する前記
回折光の強度を同一の検出器で検出する手段を具備する
ことを特徴とするアライメント装置。10. The alignment apparatus according to claim 8, wherein at least one of the left and right directions detects the intensity of each irradiation light and the intensity of the diffraction light generated by the irradiation light with the same detector. An alignment apparatus comprising:
て、照射光を左右方向から交互に照射する手段を具備す
ることを特徴とするアライメント装置。11. The alignment apparatus according to claim 7, further comprising means for irradiating the irradiation light alternately from the left and right directions.
イメント装置において、前記回折光が１次回折光である
ことを特徴とするアライメント装置。12. The alignment apparatus according to claim 8, 9, 10, or 11, wherein the diffracted light is a first-order diffracted light.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31470293A JP3351071B2 (en) | 1993-12-15 | 1993-12-15 | Alignment method and apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31470293A JP3351071B2 (en) | 1993-12-15 | 1993-12-15 | Alignment method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07167614A JPH07167614A (en) | 1995-07-04 |
| JP3351071B2 true JP3351071B2 (en) | 2002-11-25 |
Family
ID=18056527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31470293A Expired - Fee Related JP3351071B2 (en) | 1993-12-15 | 1993-12-15 | Alignment method and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3351071B2 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999056174A1 (en) * | 1998-04-30 | 1999-11-04 | Nikon Corporation | Alignment simulation |
| JP4846888B2 (en) * | 1998-12-01 | 2011-12-28 | キヤノン株式会社 | Alignment method |
| WO2000057126A1 (en) * | 1999-03-24 | 2000-09-28 | Nikon Corporation | Position determining device, position determining method and exposure device, exposure method and alignment determining device, and alignment determining method |
| JP4905617B2 (en) * | 2001-05-28 | 2012-03-28 | 株式会社ニコン | Exposure method and device manufacturing method |
| JP4085147B2 (en) | 2002-10-11 | 2008-05-14 | スパンション エルエルシー | Semiconductor device manufacturing method and manufacturing apparatus |
| EP1431833A3 (en) * | 2002-12-16 | 2009-04-15 | ASML Netherlands B.V. | Lithographic apparatus, device manufacturing method, and device manufactured thereby |
| TW200745771A (en) * | 2006-02-17 | 2007-12-16 | Nikon Corp | Adjustment method, substrate processing method, substrate processing apparatus, exposure apparatus, inspection apparatus, measurement and/or inspection system, processing apparatus, computer system, program and information recording medium |
| US7528941B2 (en) * | 2006-06-01 | 2009-05-05 | Kla-Tencor Technolgies Corporation | Order selected overlay metrology |
| DK3120107T3 (en) * | 2014-03-21 | 2019-03-18 | Carpe Diem Tech Inc | System and method for producing miniature structures on a flexible substrate |
| JP6661303B2 (en) | 2015-08-25 | 2020-03-11 | キヤノン株式会社 | Position detecting device, position detecting method, exposure apparatus and exposure method |
| CN106950221B (en) * | 2017-04-29 | 2023-11-03 | 合肥国轩高科动力能源有限公司 | Handheld coating symmetry detection device and detection method |
-
1993
- 1993-12-15 JP JP31470293A patent/JP3351071B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07167614A (en) | 1995-07-04 |
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